The 3.5in Deskstar 7K1000.B consumes 43 per cent less power than its predecessor, Hitachi said. That's in part because it uses three platters - each holding up to up to 375GB of data - rather than five, cutting the number of read/write heads from ten to six.

The 3Gb/s SATA drives also use power management techniques developed for mobile hard drives.

Hitachi said the drives provide on-board automatic data encryption based on the Advanced Encryption Standard (AES) - tough enough for the US government, apparently.

The Deskstar 7K1000.B and a version designed for 24x7 operation, the Deskstar E7K1000, go on sale later this month priced at $239 (£121/€152) and $279 (£141/€178), respectively.